1. Field of the Invention
This invention relates to a spacer for use with a breath coordinated inhaler having a connection member for the inhaler providing improved dispensing of medicament, as well as attachment, and stowage with a breath coordinated inhaler. The spacer comprises a longitudinal air chamber shaped to be held in hand and compact enough to be conveniently portable with a breath coordinated inhaler.
2. Description of the Prior Art
In the prior art, it is well known that pressurized metered dose inhalers (pMDIs) can be used to deliver aerosol drugs or other inhalants to a patient. Typically drug from pMDIs exit the spray jet orifice in the form of aerosolized particles at velocities in excess of 50 meters/second. When the aerosol particles reach the back of the throat, the velocity can be 20 meters/second or more.
Conventional pMDIs by the very nature of their drug delivery mode can produce an inconsistency in dose and region of deposition in the lung. Problems can include: a chilling effect of the propellant which may cause patients to cease the necessary inhalation maneuver prior to completion; a high velocity of aerosol which tends to encourage rapid inhalation restricting drug distribution in the lung; and the impact upon the throat of high velocity aerosol frequently causing gagging which can alter or halt the inhalation process.
To minimize these problems and to deliver the drug in a more respirable form, spacers exist that are of numerous physical shapes and designs. Some are as simple and straightforward as extension tubes placing the mouth at a greater distance from the spray. Others decelerate the aerosol by means of tortuous flow path routes or bluff body impact areas. While effective in minimizing the problems of dose delivery by conventional pMDIs, the designs used for existing spacers can contribute to the loss of drug within the spacers.
Another spacer category used to minimize the problems of conventional pMDIs are expansion chambers into which pMDIs are discharged. Medication is presented as a cloud having little or no exit impact force. An advantage is that the patient inhales the cloud created by aerosolizing a solution or suspension or dry powder with no need for concern regarding a synchronized pMDI discharge and inhalation maneuver. Problems arise with dose variability associated with retained drug. The time interval between presenting the aerosol to the chamber and inhalation may be such to cause xe2x80x9cRain Outxe2x80x9d, i.e. the settling of drug onto the walls of the chamber. xe2x80x9cRain Outxe2x80x9d can contribute to the loss of drug.
Also, material selection can cause drug loss. Since spacers must be manufactured from bio-compatible and drug compatible materials, these materials can carry an electrostatic charge. Materials which carry static charge can significantly increase drug retention in actuators and spacers.
As a result of the different design and material types of spacers as well as designs of attachment to inhalers; deposition and retention of the delivered dose of drug can be inconsistent. Because of this inconsistency, all of these devices retain drug, several over 50% requiring dispensing of larger doses to ensure adequate delivery. Since many of the drugs administered by inhalants are very expensive, more efficient delivery is an economic imperative.
Also, with few exceptions all spacers are relatively large. That is, they are not conveniently portable with the inhaler in a pocket or a purse. Those few which are smaller and part of the inhaler actuator are among those retaining the most drug; therefore, more efficient delivery in a compact spacer can be practical as well as economic in use.
Examples of prior art in this field include U.S. Pat. No. 4,534,343 entitled xe2x80x9cMetered Dose Inhalerxe2x80x9d issued to Nowacki et al. on Aug. 13, 1986; U.S. Pat. No. 4,674,491 entitled xe2x80x9cInhalerxe2x80x9d issued to Brugger et al. on Jun. 23, 1987; U.S. Pat. No. 4,796,614 entitled xe2x80x9cCollapsible Inhalation Valvexe2x80x9d issued to Nowacki et al. on Jan. 10, 1989; U.S. Pat. No. 4,852,561 entitled xe2x80x9cInhalation Devicexe2x80x9d issued to Sperry on Aug. 1, 1989; U.S. Pat. No. 4,926,852 entitled xe2x80x9cMedication Delivery System Phase Onexe2x80x9d issued to Zoltan et al on May 22, 1990; U.S. Pat. No. 5,012,803 entitled xe2x80x9cModular Medication Inhalerxe2x80x9d issued to Foley et al. on May 7, 1991; U.S. Pat. No. 5,012,804 entitled xe2x80x9cMedication Inhaler With Adult Maskxe2x80x9d issued to Foley et al. on May 7, 1991; U.S. Pat. No. 5,505,194 entitled xe2x80x9cElliptical Cylinder Portionsxe2x80x9d issued to Adjei et al. on Apr. 19, 1996; and U.S. Pat. No. 5,904,139 entitled xe2x80x9cBreath Coordinated Inhalerxe2x80x9d issued to Hauser on May 18, 1999.
It is therefore a further object of the invention to provide a spacer small enough to be incorporated as part of an inhaler actuator.
It is therefore an object of the invention to provide a spacer in which drug delivery is optimized with the use of a breath coordinated inhaler.
It is therefore a still further object of the invention to provide a spacer small enough to be used as an attachable accessory.
It is therefore a still further object of the invention to provide a spacer in which drug retention is minimized.
It is therefore a further object of the invention to provide a spacer which inhibits the velocity of inhalant to the user.
It is therefore a still further object of the invention to provide a spacer with a minimized impact of inhalant delivery to the user.
To attain the objects described the spacer will be molded to have attachment points which will be easily accommodated with the spacer docking piece of the breath coordinated inhaler sometimes referred to herein as xe2x80x9c(BCI)xe2x80x9d of U.S. Pat. No. 5,904,139, the disclosure of which is incorporated herein by reference. When used with the BCI, the spacer has the advantages of an expansion chamber without the level of drug loss. Uniformity of dose delivery can be better assured as a result of discharge synchronization, with a controlled inspiration rate and delivery of a soft plume via the spacer.
The spacer will be molded with a generally rectangular cross section with slightly curved walls. The ratio of wall height to width of the cross section is at a ratio which optimizes decelerating pMDI discharge. As a result, drug exiting the spacer has a low impact plume force of 1-5 mN and a velocity of less than 1 meter per second. Another advantage of this design is that drug retention is reduced. Combined with the spacer sealing efficiently with a breath coordinated inhaler, both the attributes of drug availability and dose uniformity will be enhanced.
Also, based upon the ratio of wall height to cross section, the spacer can be made small enough to be incorporated as part of an inhaler actuator or to be used as an attachable accessory.
Also, the spacer made of material that has a slight electrical conductivity (1 Megohm or less/cm). This slight electrical conductivity inhibits electrostatic surface effects that would otherwise attract and retain drug. This inhibition can also lead to greater drug availability and dose uniformity.
These and other objects and characteristics of the present invention will become apparent from the further disclosure to be made in the detailed description given below.